The present invention relates to vegetable oils, at least one styrene/butadiene copolymer and a pour point depressant to give a composition that has good viscometrics at both high and low temperature. The composition may also contain a performance additive to enhance the performance in areas of anti-wear, oxidation inhibition, rust/corrosion inhibition, metal passivation, extreme pressure, friction modification, viscosity modification, foam inhibition, emulsification, demulsification, lubricity, dispersancy, detergency, and the like.
Successful use of vegetable oils and other biodegradable oils as environmentally friendly base fluids in industrial applications is contingent on improving their viscometries and low temperature flow properties. For example, a sunflower oil containing an oleic acid content of 80 percent has a pour point of xe2x88x9212xc2x0 C. and turns solid in the Brookfield viscosity measurement. Many of the industrial applications require a pour point of less than xe2x88x9225xc2x0 C. and a Brookfield viscosity of 7500 to 150,000 centi poises (cP) at xe2x88x9225xc2x0 C.
U.S. Pat. No. 2,336,195 (Sparks et al, Dec. 7, 1943) relates to improving viscosity characteristics of hydrocarbon oils by the addition of normal mono-oflefin polymers. A normal mono-oflefin polymer is converted to a high molecular weight polymer by compressing an olefin, such as ethylene or propylene, to a high superatomspheric pressure in excess of 500 atmospheres.
U.S. Pat. No. 3,554,911 (Schiff et al, Jan. 12, 1971) relates to improved lubricating oils, particularly mineral lubricating oils, and processes of preparing the same. In another aspect, this reference relates to the addition of a small amount of a hydrogenated random butadiene-styrene copolymer to lubrication oils to produce formulations that are shear stable and have a high viscosity index (V.I.). Accordingly, this reference relates to hydrogenated random butadiene-styrene copolymers having defined amounts of butadiene and styrene which are blended with suitable mineral oils to increase the viscosity and improve the viscosity index.
U.S. Pat. No. 3,772,169 (Small et al, Nov. 13, 1973) provides an oil composition which comprises:
1. a lubricating oil,
2. a random copolymer of butadiene and styrene containing 30-44 percent weight of units derived from butadiene and 56-70 percent weight of units derived from styrene, which copolymer has been hydrogenated until at least 95 percent of the olefinic double bonds and at most 5 percent of the aromatic unsaturation has been saturated, and
3. an oil-soluble polyester which comprises molecular unit derived from an alkyl ester of an xcex1-olefinically unsaturated carboxylic acid in which the alkyl chain or chains contain(s) at least 7 carbon atoms.
U.S. Pat. No. 3,772,196 (St. Clair et al, Nov. 13, 1973) provides for lubricating oil compositions for internal combustion engines that have unexpectedly wide temperature operating characteristics. This composition contains a combination of a 2-block copolymer comprising a first polymer block of an alkenyl arene, e.g., styrene and a second essentially completely hydrogenated polymer block of isoprene and certain pour point depressants in a lubricant base stock having a viscosity index of at least 85.
A composition is disclosed which comprises
(A) At least one oil comprising a synthetic triglyceride, a natural oil or a derivative of a natural oil;
(B) a hydrogenated block copolymer comprising a normal block copolymer or a random block copolymer, said normal block copolymer made from a vinyl substituted aromatic and an aliphatic conjugated diene, said normal block copolymer having from two to about five polymer blocks with at least one polymer block of said vinyl substituted aromatic and at least one polymer block of said aliphatic conjugated diene, said random block copolymer made from vinyl substituted aromatic and aliphatic conjugated diene monomers, the total amount of said vinyl substituted aromatic blocks in said block copolymer being in the range of from about 20 percent to about 70 percent by weight and the total amount of said diene blocks in said block copolymer being in the range of from about 30 percent to about 80 percent by weight; the number average molecular weight of said normal block copolymer and said random block copolymer being in the range of about 5,000 to about 1,000,000; and
(C) at least one pour point depressant.
In addition to components (A), (B), and (C) the composition may also contain (D) a performance additive.